Recently, there have been severe hailstorms in Texas, causing four-inch hailstones to fall, accompanied by gusting winds of over 50 miles per hour, through utility-scale solar farms.
Whereas one solar farm directly under the most severe swath suffered major, catastrophic module damage, three adjacent solar facilities managed to avoid major financial losses by setting their single-axis trackers at a 52-degree hail stow angle.
While these sites successfully stowed prior to peak hail, industry experts now highlight fully automated weather-alert protocols as the essential standard for achieving this level of defense consistently.
Testing stow protocols during extreme Texas storms
During the month of March 2024, two successive 500-year storm systems affected Fort Bend County, Texas.
Supercells generated hailstones of up to four inches in diameter with winds reaching speeds of 51 miles per hour.
Large masses of ice caused extensive and significant damage to glass panels across the Fighting Jays solar array project, though exact technical reports on the full percentage of damaged modules remain undisclosed.
Cutlass I, Cutlass II, and Old 300 were affected by the same storm system as the Fighting Jays facility.
Each site experienced distinct hail sizes and timing.
Fighting Jays sat directly under the most intense hail swath with 75–100 mm of hail on March 16, while Old 300 saw similar large hail, and Cutlass I and II were hit by smaller 40–75 mm hail on March 15.
Operators and tracking systems at these three nearby facilities placed the panels into a 52-degree hail stow position several hours before the peak hail period hit.Solar panels were tilted to a 52-degree angle, greatly minimizing kinetic impact loads.
While varying hail exposure played a role in the overall outcomes, the three array-equipped sites demonstrated that stowing protected panels, incurring minor or no damage across stowed rows.
Rotating panels significantly diverted hailstones from falling directly onto the panels.
Correcting flawed historical hail risk maps
For decades, solar power developers have used federal emergency management maps to estimate regional hail dangers.
Legacy maps classified Fort Bend County as having a low to medium risk of hail.
Engineers addressed the population bias in maps through the inclusion of information from Doppler radar tracking and professional spotters’ observations.
The mapping of return intervals in the radar shows that Eastern Texas is actually at high risk of giant hail.
Radar mapping ensures that investors obtain realistic risk profiles of the environment.
The use of legacy risk maps is overcome through accurate radar maps that allow the right pricing of insurance.
Automating rapid response tracking software
Manual stowing is often ineffective for sudden storms that occur overnight unexpectedly.
The storm of March 16 occurred in Fort Bend County at 2:30 a.m.
The occurrence of surprising night storms demands SCADA system integration with automated weather alerts from authorized agencies.
To ensure consistent protection, industry guidelines from VDE Americas now recommend configuring SCADA software.
This will automatically trigger a stow cycle whenever there is a 30% or higher probability of severe hail within 30 miles.
Industry best practices dictate that automated weather alerts communicate directly with tracking motors—rather than relying on email or manual human intervention—to ensure rapid positioning during sudden overnight events.
Quick action saves the expensive solar system from any damage caused by the sudden development of storm cells.
Reinforcing hardware durability with thicker glass
The majority of utility solar projects in the USA employ dual-glass bifacial panels composed of 0.08-inch heat-strengthened glass.
Two-inch hail impacts on 0.08-inch glass will result in extensive micro-cracks.
Switching to 0.13-inch tempered front glass improves total impact resistance two times over.
In combination with automatic 52-degree stow technology, thick tempered glass protects installations from heavy ice impacts.
Better hardware selection results in decreased financial risks for projects’ underwriters.
Hardware investments eliminate the chances of problems occurring in the long run, according to VDE Americas.
Identifying operational limits of defensive stowing
Automatic stow protocol decreases the risk of loss, but defensive positioning cannot totally eliminate risks due to the weather.
Strong wind gusts caused by a storm that includes hail can result in un-stowed panels being flattened if the motors experience electrical failures.
In Old 300, one motor failure resulted in approximately 40 solar panels failing to stow and subsequently causing hail damage to this area alone.
Predicting changes in wind direction when a hail storm occurs is also incredibly difficult with automated weather models.
It is ideal for stowing modules away from where the wind blows, but storm winds usually tend to shift unpredictably.
Stow protocol implementation decreases millions of dollars worth of risk.
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